Animation:
Animated GIFs: One GIF file can hold a series of images that it can cycle through. The small animation can play just once, or it can repeat a specified number of times, or continuously. Of course, the more frames that it holds or the bigger it is, the longer download time is.

Other file types like "Flash" and "Shockwave" can be seen if the appropriate plug-in is available in the plug-ins folder of your browser. The latest browsers come with all the plug-ins you need to view the latest media technology on the Web so it's usually easier to just download the browser you want instead of locating the desired plug-in.